Integrated abrasive polishing pads and manufacturing methods

ABSTRACT

Embodiments described herein relate to integrated abrasive (IA) polishing pads, and methods of manufacturing IA polishing pads using, at least in part, surface functionalized abrasive particles in an additive manufacturing process, such as a 3D inkjet printing process. In one embodiment, a method of forming a polishing article includes dispensing a first plurality of droplets of a first precursor, curing the first plurality of droplets to form a first layer comprising a portion of a sub-polishing element, dispensing a second plurality of droplets of the first precursor and a second precursor onto the first layer, and curing the second plurality of droplets to form a second layer comprising portions of the sub-polishing element and portions of a plurality of polishing elements. Here, the second precursor includes functionalized abrasive particles having a polymerizable group chemically bonded to surfaces thereof.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application claims benefit of U.S. Provisional Patent ApplicationSer. No. 62/537,290 filed on Jul. 26, 2017 which is herein incorporatedby reference in its entirety.

BACKGROUND Field

Embodiments of the present disclosure generally relate to a polishingpad, and methods of forming a polishing pad, and more particularly, to apolishing pad used for polishing a substrate in an electronic devicefabrication process.

Description of the Related Art

Chemical mechanical polishing (CMP) is commonly used in the manufactureof high-density integrated circuits to planarize or polish a layer ofmaterial deposited on a substrate, by contacting the material layer tobe planarized with a polishing pad and moving the polishing pad and/orthe substrate, and hence the material layer surface, in the presence ofa polishing fluid and abrasive particles. Two common applications of CMPare planarization of a bulk film, for example pre-metal dielectric (PMD)or interlayer dielectric (ILD) polishing, where underlying featurescreate recesses and protrusions in the layer surface, and shallow trenchisolation (STI) and interlayer metal interconnect polishing, wherepolishing is used to remove the via, contact or trench fill materialfrom the exposed surface (field) of the layer having the feature.

In a typical CMP process, the substrate is retained in a carrier headthat presses the backside of the substrate toward the polishing pad.Material is removed across the material layer surface in contact withthe polishing pad through a combination of chemical and mechanicalactivity that is provided by the polishing fluid and the abrasiveparticles. Typically, the abrasive particles are either suspended in thepolishing fluid, known as a slurry, or are embedded in the polishingpad, known as a fixed abrasive polishing pad.

When abrasive particles are suspending in the polish fluid (slurry) anon-abrasive polishing pad is typically used to transport the abrasiveparticles to the material layer of the substrate where the abrasiveparticles provide mechanical action, and in some embodiments, chemicalreaction, with the surface thereof. In contrast, with a fixed abrasivepolishing pad, the abrasive particles are typically integrated into thepolishing pad by embedding them in a supporting material (e.g., oftenreferred to as a binder material), such as an epoxy resin. Generally,during a CMP process, the binder material fixedly holds the abrasiveparticles in place at the polishing pad surface where they providemechanical polishing action to, and sometimes chemical reaction with,the material layer of the substrate during the CMP process.

Generally, fixed abrasive polishing pads are superior to standard(non-fixed abrasive polishing pads) in some aspects of polishingperformance, such as less undesirable erosion of planar surfaces inareas with high feature density and less undesirable dishing of theupper surface of the film material in recessed features such astrenches, contacts, and lines. However, fixed abrasive polishing padstend to have lower lifetimes (polishes per pad), inferior substrate tosubstrate stability for film removal rate from the substrate surface,and inferior substrate to substrate stability for uniformity of filmremoval across the substrate.

Typically, fixed abrasive conditioning disks, such as diamondconditioning disks, are used with standard polishing pads to rejuvenateand planarize the polishing pad surface, and thus maintain substrate tosubstrate stability polishing performance. However, fixed abrasiveconditioning disks are generally incompatible for use with fixedabrasive polishing pads as the disk will remove the embedded abrasiveparticles from the inherently brittle surface of the supporting epoxymaterial in which the abrasive material is embedded. This undesirableremoval of the abrasive particles leaves a pad surface devoid, or nearlydevoid, of the abrasive particles necessary for efficient CMP processes.

Accordingly, what is needed in the art is a polishing pad, and methodsof manufacturing a polishing pad, having desirable polishingcharacteristics of a fixed abrasive polishing pad that is compatiblewith external conditioning, such as with a fixed abrasive conditioningdisk.

SUMMARY

Embodiments herein generally relate to an integrated abrasive (IA)polishing pad comprising abrasive particles disposed in, and chemicallybonded to, the polishing material of portions of the polishing pad, andmethods of forming thereof. In particular, in embodiments herein, acurable resin precursor mixture is formed with abrasive particles havinga polymerizable group chemically bonded to surfaces thereof. The curableresin precursor mixture is used in an additive manufacturing process,along with a curable resin sub-polishing material precursor composition,to form a polishing pad. In some embodiments, the polishing pad hasdiscrete polishing elements with abrasive particles disposed in, andchemically bonded to, the polishing pad material thereof.

In one embodiment, a method of forming a polishing article includesdispensing a first plurality of droplets of a first precursor and curingthe first plurality of droplets to form a first layer comprising aportion of a sub-polishing element. The method further includesdispensing a second plurality of droplets of the first precursor and asecond precursor onto the first layer and curing the second plurality ofdroplets to form a second layer comprising portions of the sub-polishingelement and portions of a plurality of polishing elements. Here, thesecond precursor includes functionalized abrasive particles having apolymerizable group chemically bonded to surfaces thereof.

In another embodiment, a method of forming a polishing article includesforming a sub-polishing element from a first plurality of droplets of afirst precursor and forming a plurality of polishing elements disposedin, and extending from, the sub-polishing element by dispensing a secondplurality of droplets of a second precursor. Here, the second precursorcomprises treated metal oxide nanoparticles having polymerizablecompounds bonded to less than about 50% of bonding sites on the surfaceof the metal oxide nanoparticles. The treated metal oxide nanoparticlescomprise the reaction product of metal oxide nanoparticles with a silanecompound, a cyanate compound, a sulfonic acid compound, a phosphoricacid compound, a carboxylic acid compound, or combinations thereof.

In another embodiment, a polishing article includes a sub-polishingelement comprising a first reaction product of a first precursor mixtureand a plurality of polishing elements extending from the sub-polishingelement. Here, the plurality of polishing elements comprise a secondreaction product of a second precursor mixture, wherein the secondprecursor mixture comprises functionalized abrasive particles.

BRIEF DESCRIPTION OF THE DRAWINGS

So that the manner in which the above recited features of the presentdisclosure can be understood in detail, a more particular description ofthe disclosure, briefly summarized above, may be had by reference toembodiments, some of which are illustrated in the appended drawings. Itis to be noted, however, that the appended drawings illustrate onlytypical embodiments of this disclosure and are therefore not to beconsidered limiting of its scope, for the disclosure may admit to otherequally effective embodiments.

FIGS. 1A-1D illustrate various properties of surface functionalizedceria particles formed according methods set forth herein.

FIG. 2A is a schematic sectional view of a polishing system using anintegrated abrasive (IA) polishing pad formed according to embodimentsdisclosed herein.

FIGS. 2B-2C are schematic perspective sectional views of IA polishingpads, according to embodiments described herein.

FIG. 3A is a schematic sectional view of an additive manufacturingsystem used to form an integrated abrasive (IA) polishing pad, such asthe IA polishing pads described in FIGS. 2B-2C, according to oneembodiment.

FIGS. 3B and 3C illustrate a curing process using the additivemanufacturing system described in FIG. 3A.

FIGS. 4A-4B illustrate the properties of a layer formed from a precursorcomprising surface functionalized abrasive particles, according to oneembodiment.

FIG. 5 is a flow diagram illustrating a method of forming a polishingpad, such as the integrated abrasive (IA) polishing pads described inFIG. 2A-2B, according to one embodiment.

FIG. 6 is a schematic top view of an integrated abrasive (IA) polishingpad, according to another embodiment.

To facilitate understanding, identical reference numerals have beenused, where possible, to designate identical elements that are common tothe figures. It is contemplated that elements disclosed in oneembodiment may be beneficially utilized on other embodiments withoutspecific recitation.

DETAILED DESCRIPTION

Embodiments described herein generally relate to polishing articles andmethods for manufacturing polishing articles used in a polishingprocess. More specifically, embodiments described herein relate tointegrated abrasive (IA) polishing pads, and methods of manufacturing IApolishing pads, that have the advantageous polishing characteristics offixed abrasive polishing pads yet allow for conditioning with a fixedabrasive conditioner, such as a diamond conditioner. The ability tocondition IA polishing pads enables a polishing process that uses anon-abrasive polishing fluid yet has stable and controlled polishingperformance and an extended polishing pad lifetime.

Herein the polishing articles described as polishing pads, and methodsof forming thereof, are applicable to other polishing applicationsincluding, for example, buffing. Further, although the discussion hereinis in relation to chemical mechanical polishing (CMP) processes, thearticles and methods are also applicable to other polishing processesusing both chemically active and chemically inactive polishing fluids.In addition, embodiments described herein may be used in at least thefollowing industries: aerospace, ceramics, hard disk drive (HDD), MEMSand Nano-Tech, metalworking, optics and electro-optics manufacturing,and semiconductor device manufacturing, among others.

Embodiments of the present disclosure provide for integrated abrasive(IA) polishing pads manufactured using, at least in part, surfacefunctionalized abrasive particles in an additive manufacturing process,such as a two-dimensional 2D or three-dimensional 3D inkjet printingprocess. Additive manufacturing processes, such as the three-dimensionalprinting (“3D printing”) process described herein, enable the formationof polymer IA polishing pads with discrete polishing regions and/orpolishing features (polishing elements) having unique properties andattributes. Generally, the polymers of the polishing elements formchemical bonds, for example covalent bonds or ionic bonds, with thepolymers of adjacent polishing elements at the interfaces thereof.Because the polishing elements are linked with adjacent polishingelements through chemical bonding, the interfaces are stronger and morerobust than polishing pads having discrete elements attached using othermethods, such as with adhesive layers or by thermal bonding, to allowfor the use of a more aggressive polishing or conditioning process whendesired.

Herein, abrasive particles refer to hydroxyl terminated metal oxidenanoparticles such as single or multicomponent metal oxidenanoparticles, for example ceria, alumina, silica, silica/alumina oxide,or combinations thereof. In other embodiments, the abrasive particlescomprise metal oxide nanoparticles terminated with hydroxyl groups,thiol groups, carboxylic acid groups, amino groups, or combinationsthereof. A surface functionalized abrasive particle refers to anabrasive particle comprising at least one polymerizable group chemicallybonded to bonding sites on the surfaces thereof. Bonding sites refers tosites that can react with the compounds described herein to form acovalent bond with a polymerizable group.

In some embodiments, surface modification to achieve the surfacefunctionalized abrasive particle includes reacting the surfaces of thehydroxyl terminated abrasive particles with surface modifying organiccompounds, such as organic silane compounds, sulfonic acid compounds,organic phosphoric acid compounds, carboxylic acid compounds,derivatives thereof, or combinations thereof. In embodiments describedherein, the reaction product of the hydroxyl terminated abrasiveparticles comprises abrasive particles having surfaces terminated withboth alkene and hydroxyl groups, hereafter referred to as alkeneterminated abrasive particles. In other embodiments, the surfaces may beterminated with any polymerizable group, such as an epoxy group, forexample an epoxy aldehyde group or an epoxy ketone group.

In one embodiment, the surface functionalized abrasive particles areformed by reacting the surfaces of the abrasive particles with a silanecompound, such as an alkoxy silane, such as trichloro(phenyl)silane,trichloro(hexyl)silane, trichloro(octadecyl)silane,trimethoxy(7-octen-1-yl)silane, trichloro[2-(chloromethyl)allyl]silane,vinyltrimethoxysilane, chloro(dimethyl)vinylsilane,allyltrimethoxysilane, acryloyl chloride, vinyltrimethoxysilane, orcombinations thereof. The abrasive particle silane compound reaction isused to graft a desired polymerizable group onto a hydroxyl terminatedsurface of the abrasive particle (i.e., circular shaped element shownbelow) as represented in chemical reactions (A) and (B) where R is amethyl group (CH₃).

In another embodiment, the surface functionalized abrasive particles areformed by reacting the surfaces of the abrasive particles with a cyanatecompound, such as an isocyanate based monomer such astris-[3-(trimethoxysilyl)propyl] isocyanurate or2-(methacryloyloxy)ethyl isocyanate. For example, the isocyanate groupof 2-(methacryloyloxy)ethyl isocyanate reacts with hydroxyl group andform amide bond results in covalent linkage of acrylic groups withabrasive nanoparticles as shown in chemical reaction (C) where Rrepresents hydrogen (H) or a methyl group (CH₃).

In another embodiment, the surface functionalized abrasive particles areformed by reacting the surfaces of the abrasive particles with sulfonicor phosphoric acid derivatives, such as2-acrylamido-2-methyl-1-propanesulfonic acid as shown in reaction (D) orwith vinyl phosphonate as shown in reaction (E), where R representshydrogen (H) or a methyl group (CH₃).

In another embodiment, the surface functionalized abrasive particles areformed by reacting the surfaces of the abrasive particles withcarboxylic acids that comprise acrylic groups, such as shown in chemicalreaction (F) where R represents hydrogen (H) or a methyl group (CH₃) andn is from 1 to 50. In some embodiments, the reactivity of the carboxylicgroup is increased by converting the carboxylic acid containing acrylicgroup to a chloride acid using thionyl chloride.

FIGS. 1A-1D illustrate various properties of surface functionalizedceria particles formed according to one embodiment. Ceria is commonlyused as an abrasive particle for shallow trench isolation (STI)polishing applications in addition to other CMP applications because thehydroxyl terminated surface of ceria exhibits a high affinity forsilicon oxide (SiO₂) materials compared to silicon nitride materialsleading to desirably high selectivity between the two films. While notwishing to be bound to a particular theory it is believed that excessiveloading (% of bonding sites) of the surface of ceria particles withpolymerizable groups will undesirably influence the reaction of theceria particle with an H-terminated surface of SiO₂ which impactspolishing rate and selectivity performance. Therefore, it is desirableto limit the loading of functionalized surface sites on the surfaces ofthe ceria particles so that sufficient hydroxyl terminated sites remainto react with the H-terminated surfaces of SiO₂. Herein, loading of theabrasive particles surfaces, such as ceria surfaces, with polymerizablegroups is desirably maintained at between about 0.1% and about 50%, suchas between about 1% and about 25%, such as between about 1% and about10%, such as between about 1% and about 5%, for example between about 2%and about 5%, or where at least some of the abrasive particle surfacesare surface functionalized by not more than about 5%.

In FIGS. 1A-1D ceria particles were surface functionalized by reactingthe hydroxyl terminated surface sites with chloro(dimethyl)vinylsilaneas shown in reaction (G).

The reaction was carried out by mixing ceria particles with anon-aqueous solvent, such as toluene, while using a probe sonicator toagitate the mixture at 60° C. Chloro(dimethyl)vinylsilane was added tothe mixture drop by drop during sonication and the mixture was thenmaintained at 60° C. for about three hours to complete the reaction andprovide for surface functionalized ceria particles. The surfacefunctionalized ceria particles were purified by a combination offiltration, centrifugation, and washing with toluene to remove theunreacted chloro(dimethyl)vinylsilane. The treated ceria particles werecharacterized with thermogravimetric analysis (TGA), Fourier transforminfrared spectroscopy (FTIR), transmission electron microscopy (TEM),and energy dispersive x-ray (EDX) analysis to confirm functionalizationthereof.

FIG. 1A shows the results of a thermogravimetric analysis (TGA) of asample of the treated ceria particles. As the sample of treated ceriaparticles 107 was heated from ambient temperature to 100° C. (firstrange 103) it experienced rapid weight loss attributable to theevaporation of the residual toluene left from the purification process.A second range 105 of temperatures from 100° C. to 800° C., and, inparticular, from 400° C. to 800° C. show a more gradual decline in theweight of the sample of treated ceria particles which is attributable tothe ignition of the hydrocarbons of the polymerizable groups bonded tothe bonding sites on the surfaces thereof. FIG. 1B shows the results ofan FTIR analysis of the treated ceria particles 107 compared tountreated ceria particles 111. A CH═CH₂ vibration 119 at a wavelength ofabout 1620 cm⁻¹ and methyl antisymmetric and symmetric vibrations 117 atabout 2919 cm⁻¹ and 2850 cm⁻¹ indicate successful surface modification,and thus surface functionalization, of the treated ceria particles 107with dimethyl vinyl silane groups when compared to the untreated ceriaparticles 111. An O—H vibration 115 at about 3400 cm⁻¹ indicates that aportion of the hydroxyl groups on the treated ceria particles 107 havebeen consumed during the reaction when compared to the untreated ceriaparticles 111, further indicating successful surface functionalizationof the treated ceria particles 107 with dimethyl vinyl silane groups.However, as shown by O—H vibration 115 at least a portion of thehydroxyl groups remain bonded to bonding sites of the surfaces of thetreated ceria particles 107 thus leaving sufficient hydroxyl terminatedsites on the ceria particle maintain desirable polishing rates and/orselectivity performance during a CMP process, such as during an STIpolishing process where the hydroxyl terminated sites of ceria particlesreact with H-terminated surfaces of SiO₂.

FIG. 1C shows TEM images 120 and 130 where drop-coated films of thetreated ceria particles 107 were formed on carbon-coated copper grindsby solvent evaporation. As shown in images 120 and 130 the individualtreated ceria particles have a fairly uniform mean diameter of betweenabout 20 nm to about 50 nm. However, not unexpectedly, the individualparticles formed larger agglomerations of particles that, in a typicalformulation, will need to be milled, meaning the larger agglomerationsof particles will need to be separated into smaller agglomerationsand/or individual particles before or during formulation of theprecursor mixtures used to form the IA polishing pad described herein.FIG. 1D shows selected EDX spectra of the treated ceria particles shownin image 145, where Ce, O, and Si signals are attributable to ceriaparticles and the bonded dimethyl vinyl silane group, indicatingsuccessful functionalization of the treated ceria particles' surfaceswith the polymerizable dimethyl vinyl silane group. In anotherembodiment, the surfaces of the abrasive particles are reacted with thesurface modifying compounds using a vapor reaction process, such as afluidized bed.

FIG. 2A is a schematic sectional view of an example polishing system 250using an IA polishing pad 200 formed according to the embodimentsdescribed herein. Typically, the IA polishing pad 200 is secured to aplaten 252 of the polishing system 250 using an adhesive, such as apressure sensitive adhesive, disposed between the IA polishing pad 200and the platen 252. A substrate carrier 258, facing the platen 252, andthe IA polishing pad 200 mounted thereon, has a flexible diaphragm 261configured to impose different pressures against different regions of asubstrate 260 while urging the material surface of the substrate 260against the polishing surface of the IA polishing pad 200. The substratecarrier 258 includes a carrier ring 259 surrounding the substrate 260.During polishing, a downforce on the carrier ring 259 urges the carrierring 259 against the IA polishing pad 200 to prevent the substrate 260from slipping from the substrate carrier 258. The substrate carrier 258rotates about a carrier axis 264 while the flexible diaphragm 261 urgesthe substrate 260 against the polishing surface of the IA polishing pad200. The platen 252 rotates about a platen axis 254 in an oppositedirection from the rotation of the substrate carrier 258 while thesubstrate carrier 258 sweeps back and forth from an inner diameter ofthe platen 252 to an outer diameter of the platen 252 to, in part,reduce uneven wear of the IA polishing pad 200. Herein, the platen 252and the IA polishing pad 200 have a surface area that is greater than asurface area of the substrate 260, however, in some polishing systems,the IA polishing pad 200 has a surface area that is less than thesurface area of the substrate 260.

During polishing, a fluid 226 is introduced to the IA polishing pad 200through a fluid dispenser 268 positioned over the platen 252. Typically,the fluid 226 is water, a polishing fluid, a polishing slurry, acleaning fluid, or a combination thereof. Herein, the polishing fluidcontains a pH adjuster and/or chemically active components, such as anoxidizing agent, to enable chemical mechanical polishing of the materialsurface of the substrate 260.

Typically, the polishing system 250 includes a pad conditioning assembly270 that comprises a conditioner 278, such as a fixed abrasiveconditioner, for example a diamond conditioner. The conditioner 278 iscoupled to a conditioning arm 272 having an actuator 276 that rotatesthe conditioner 278 about its center axis. while a downforce is appliedto the conditioner 278 as it sweeps across the IA polishing pad 200before, during, and/or after polishing the substrate 260. Theconditioner 278 abrades and rejuvenates the IA polishing pad 200 and/orcleans the IA polishing pad 200 by removing polish byproducts or otherdebris from the polishing surface thereof.

FIGS. 2B-2C are schematic perspective sectional views of IA polishingpads 200 b-c, according to embodiments described herein. The IApolishing pads 200 b-c can be used as the IA polishing pad 200 in thepolishing system 250 of FIG. 2A. In FIG. 2B, the IA polishing pad 200 bcomprises a plurality of polishing elements 204 b that are disposedwithin a sub-polishing element 206 b, and extend from a surface of thesub-polishing element 206 b. The plurality of polishing elements 204 bhave a thickness 215 the sub-polishing element 206 b has a sub-thickness212. As illustrated in FIGS. 2B and 2C, the polishing elements 204 b,204 c are supported by a portion of the sub-polishing element 206 b, 206c (e.g., portion within region 212A). Therefore, when a load is appliedto the polishing surface 201 of the IA polishing pads 200 b-c (e.g., topsurface) by a substrate during processing, the load will be transmittedthrough the polishing elements 204 b, 204 c and portion 212A of thesub-polishing element 206 b, 206 c. Herein, the plurality of polishingelements 204 b include a post 205 disposed in the center of the IApolishing pad 200 b and a plurality of concentric rings 207 disposedabout the post 205 and extending radially outward therefrom. Theplurality of polishing elements 204 b and the sub-polishing element 206b define a plurality of channels 218 disposed in the IA polishing pad200 b between each of the polishing elements 204 b and between a planeof the polishing surface of the IA polishing pad 200 b and a surface ofthe sub-polishing element 206 b. The plurality of channels 218 enablethe distribution of fluid 266, such as a polishing fluid, across the IApolishing pad 200 b and to an interface between the IA polishing pad 200b and the material surface of a substrate 260. In other embodiments, thepatterns of the polishing elements 204 b are rectangular, spiral,fractal, random, another pattern, or combinations thereof. Herein, awidth 214 of the polishing element(s) 204 b-c is between about 250microns and about 5 millimeters, such as between about 250 microns andabout 2 millimeters. A pitch 216 between the polishing element(s) 204 bis between about 0.5 millimeters and about 5 millimeters. In someembodiments, the width 214 and/or the pitch 216 varies across a radiusof the IA polishing pad 200 b to define zones of pad material propertiesand/or abrasive particle concentration.

In FIG. 2C, the polishing elements 204 c are shown as circular columnsextending from the sub-polishing element 206 c. In other embodiments,the polishing elements 204 b are of any suitable cross-sectional shape,for example columns with toroidal, partial toroidal (e.g., arc), oval,square, rectangular, triangular, polygonal, irregular shapes, orcombinations thereof. In some embodiments, the shapes and widths 214 ofthe polishing elements 204 c, and the distances therebetween, are variedacross the IA polishing pad 200 c to tune hardness, mechanical strength,fluid transport characteristics, or other desirable properties of thecomplete IA polishing pad 200 c.

Herein, the polishing elements 204 b-c and the sub-polishing elements206 b-c each comprise a pad material composition of at least one ofoligomeric and/or polymeric segments, compounds, or materials selectedfrom the group consisting of: polyamides, polycarbonates, polyesters,polyether ketones, polyethers, polyoxymethylenes, polyether sulfone,polyetherimides, polyimides, polyolefins, polysiloxanes, polysulfones,polyphenylenes, polyphenylene sulfides, polyurethanes, polystyrene,polyacrylonitriles, polyacrylates, polymethylmethacrylates, polyurethaneacrylates, polyester acrylates, polyether acrylates, epoxy acrylates,polycarbonates, polyesters, melamines, polysulfones, polyvinylmaterials, acrylonitrile butadiene styrene (ABS), halogenated polymers,block copolymers and random copolymers thereof, and combinationsthereof.

In some embodiments, the materials used to form portions of the IApolishing pad 200 b-c, such as the first polishing elements 204 b-c andthe sub-polishing elements 206 b-c will include the reaction product ofat least one ink jettable pre-polymer composition that is a mixture offunctional polymers, functional oligomers, reactive diluents, and curingagents to achieve the desired properties of an IA polishing pad 200 b-c.In general, the deposited material can be exposed to heat orelectromagnetic radiation, which may include ultraviolet radiation (UV),gamma radiation, X-ray radiation, visible radiation, IR radiation, andmicrowave radiation and also accelerated electrons and ion beams may beused to initiate polymerization reactions. For the purposes of thisdisclosure, we do not restrict the method of cure, or the use ofadditives to aid the polymerization, such as sensitizers, initiators,and/or curing agents, such as through cure agents or oxygen inhibitors.In one embodiment, two or more polishing elements, such as the polishingelements 204 b-c and the sub-polishing elements 206 b-c, within aunitary pad body, are formed from the sequential deposition and postdeposition processing and comprise the reaction product of at least oneradiation curable resin precursor composition, wherein the compositionscontain functional polymers, functional oligomers, monomers, and/orreactive diluents that have unsaturated chemical moieties or groups,including but not restricted to: vinyl groups, acrylic groups,methacrylic groups, allyl groups, and acetylene groups. The hardnessand/or storage modulus E′ of the materials found within the polishingelements 204 b-c and the sub-polishing elements 206 b-c are different,such that the values hardness and/or storage modulus E′ values for thepolishing elements 204 b-c elements are greater than the sub-polishingelements 206 b-c elements. In some embodiments, the material compositionand/or material properties of the polishing elements 204 b-c vary frompolishing element to polishing element. Individualized materialcomposition and/or material properties allow for the tailoring of thepolishing pads for specific needs.

At least a portion of the one or more of the plurality of polishingelements 204 b-c include abrasive particles disposed in, and chemicallybonded, either covalently or ionically, to the polishing pad materialcompositions thereof. Herein, the polishing elements 204 b-c comprise,at least, the reaction product of a radiation curable resin precursorcomposition that contains functional polymers, functional oligomers,monomers, or reactive diluents that have unsaturated chemical moietiesor groups, including but not restricted to: vinyl groups, acrylicgroups, methacrylic groups, allyl groups, and acetylene groups, andsurface functionalized abrasive particles, such as alkene terminatedabrasive particles, for example alkene terminated metal oxidenanoparticles. Typically, the concentration of the abrasive particles isless than about 70 wt. % of the polishing pad material composition ofthe polishing element 204 b, such as less than about 50 wt. %, such asbetween about 1 wt. % and about 50 wt. %, between about 1 wt. % andabout 40 wt. %, between about 1 wt. % and about 30 wt. %, between about1 wt. % and about 20 wt. %, between about 1 wt. % and about 10 wt. %,for example between about 1 wt. % and about 5 wt. %. Herein, the surfacefunctionalized abrasive particles are uniformly distributed throughoutthe polishing elements 204 b-c.

In other embodiments, the surface functionalized abrasive particles areuniformly distributed in the portion of the polishing elements 204 b-cextending from the surface of the sub-polishing elements 206 b-c andabrasive particles are not included in the polishing pad material in theportion of the polishing element 204 b-c extending beneath the surfaceof the sub-polishing element 206 b-c. In other embodiments, theconcentration of the abrasive particles increases or decreased fromfirst ends of the polishing elements 204 b-c to second ends of thepolishing elements 204 b-c distal from the first ends where the secondends form polishing surfaces of the IA polishing pads 200 b-c. In otherembodiments, the abrasive particles are disposed in abrasive layers ofthe polishing elements with layers of pad material (non-abrasive layers)comprising no abrasive particles, or lower concentrations of abrasiveparticles, disposed therebetween. In some embodiments, the IA polishingpads 200 b-c further include abrasive particles disposed in, andchemically bonded to, the polishing pad material compositions of thesub-polishing elements 206 b-c.

Typical polishing pad material composition properties that may beadjusted using the methods and material compositions described hereininclude storage modulus E′, loss modulus E″, hardness, tan δ, yieldstrength, ultimate tensile strength, elongation, thermal conductivity,zeta potential, mass density, surface tension, Poison's ratio, fracturetoughness, surface roughness (R_(a)), glass transition temperature (Tg)and other related properties. For example, storage modulus E′,influences polishing results such as the removal rate from, and theresulting uniformity of, the material layer surface of a substrate.Typically, polishing pad material compositions having a medium or highstorage modulus E′ provide a higher removal rate for dielectric filmsused for PMD, ILD, and STI, and cause less undesirable dishing of theupper surface of the film material in recessed features such astrenches, contacts, and lines. Polishing pad material compositionshaving a low storage modulus E′ generally provide more stable removalrates across the polishing pad lifetime, cause less undesirable erosionof a planer surface in areas with high feature density, and causereduced micro scratching of the material surface. In general, polishingpad material compositions with a low storage modulus are unsuitable as abinder material for the abrasive particles of a conventional fixedabrasive polishing pad as the abrasive particles can more easily escapethe softer pad material than with a hard, high storage modulus E′,conventional epoxy resin type of supporting material. Characterizationsas a low, medium, or high storage modulus E′ pad material composition attemperatures of 30° C. (E′30) and 90° C. (E′90) are summarized in Table1:

TABLE 1 Low Storage Modulus Medium Modulus High Modulus CompositionsCompositions Compositions E′30 5 MPa-100 MPa 100 MPa-500 MPa 500MPa-3000 MPa E′90 <17 MPa <83 MPa <500 MPa

Typically, the sub-polishing elements 206 b-c are formed from materialsdifferent from the materials forming the polishing elements 204 b-c,such as materials having a low (soft) or moderate storage modulus E′.The polishing elements 204 b-c are typically formed from materialshaving a medium or high (hard) storage modulus E′. With a standardnon-abrasive polishing pad and slurry process, medium or high storagemodulus polishing materials are generally necessary to maintaindesirable material removal rates when polishing dielectric materials,such as SiO₂. This is because the harder pad materials more effectivelyhold or support the loose abrasive particles against the materialsurface of the substrate when compared to a softer pad that will allowthe abrasive particles to sink below the pad surface as the pad materialdeforms when a downforce pushes the substrate against the surface of thepolishing pad. Also, it has been found that CMP processes that use softor low storage modulus E′ polishing pads tend to have non-uniformplanarization results due to the relative ease that a soft or lowstorage modulus E′ polishing pad deforms under the applied forcegenerated by the carrier ring 259 (FIG. 2A) and the applied forcegenerated by the flexible diaphragm 261 during a CMP process. In otherwords, the soft, flexible and low storage modulus E′ nature of thematerial used to form the soft or low storage modulus E′ polishing padallows the effect that the force, supplied by the carrier ring 259, tobe minimized, which improves the ability of the pad to compensate forcarrier ring downforce. Likewise, conventional fixed abrasive polishingpads typically utilize a material that has a high hardness value tophysically hold the abrasive particles in place. However, it has beenfound that CMP processes that use “hard” polishing pad materials tend tohave non-uniform planarization results due to edge effects found at theedge of the polished substrate 260 (FIG. 2A) that specifically relate tothe need to apply a force to the carrier ring 259 (FIG. 2A) tocompensate for a larger inherent polishing non-uniformity found at theedge of the substrate during a CMP process. It is believed that one ofthe benefits of the IA polishing pads described herein is the ability tomaintain high removal rates and low erosion where the polishing elements204 b-c comprise a polishing pad material composition having a tunedand/or controlled low or medium storage modulus E′. This is because thedesirably positioned abrasive particles, will be held at the padsurface, through covalent bonding thereto, instead of sinking into thesoft pad material as with a standard soft polishing pads and slurryprocess. By holding the abrasive particles at the polishing surface of asoft pad material, the chemical activity between the abrasive particleand the material surface of the substrate, such as a between a ceriaparticle and an SiO₂ substrate surface, can be maintained to enable areasonable material removal rate. Therefore, in some embodiments thepolishing elements 204 b-c will have a low or medium storage modulus E′.However, it is also recognized that surface functionalized abrasiveparticles act as a crosslinking reagent between polymer chains formedfrom the radiation curable resin precursor composition. In someembodiments, this function as a crosslinking reagent will lead to ahigher storage modulus E′ for the polishing elements 204 b-c, dependingon the loading of the polymerizable terminated bonding sites, such asalkene terminated bonding sites, on the abrasive particle and/or theconcentration of the surface functionalized abrasive particles in theradiation curable resin precursor composition. Therefore, in someembodiments, it is desirable to limit the loading (% of polymerizablegroup terminated bonding sites on surfaces of the abrasive particles) ofthe polymerizable group, such as the loading of alkene terminatedgroups, to less than about 10%, such as less than about 5%, for examplebetween 2% and 5%.

In addition to anchoring abrasive particles to the polishing surfaces ofthe polishing elements 204 b-c, by chemically bonding the abrasiveparticles to the polishing material thereof, functionalizing thesurfaces of the abrasive particles also increases the chemicalcompatibility of the precursor compositions used to manufacture thepolishing pads in an additive manufacturing process, such as the 3Dinkjet printing process described in FIGS. 3A-3C.

FIG. 3A is a schematic sectional view of an additive manufacturingsystem 350 used to form an IA polishing pad, such as IA polishing pads200 b-c, according to embodiments disclosed herein. Herein, the additivemanufacturing system 350 has a first printer 360 and a second printer370 for dispensing droplets of a first precursor composition 359 and asecond precursor composition 369 through one or more dispense nozzles335. The printers 360 and 370 move independently of one another andindependently of a manufacturing support 302 during the printing processwhich enables the placement of droplets of the precursor compositions359 and 369 at selected locations on the manufacturing support 302 toform a polishing pad, such as the IA polishing pads 200 b-c. Theselected locations are collectively stored as a CAD-compatible printingpattern which is readable by an electronic controller 305 which directsthe motion of the manufacturing support 302, the motion of the printers360 and 370, and delivery of the droplets from the nozzles 335.

Typically, the first precursor composition 359 is used to form thesub-polishing elements 206 b-c and the second precursor composition 369is used to form the plurality of polishing elements 204 b-c of the IApolishing pads 200 b-c shown in FIGS. 2B-2C. Herein, the first andsecond precursor compositions 359 and 369 each comprise a mixture of oneor more of functional polymers, functional oligomers, monomers, and/orreactive diluents that are at least monofunctional, and undergopolymerization when exposed to free radicals, Lewis acids, and/orelectromagnetic radiation. In some embodiments, the first and/or secondprecursor compositions 359 and 369 further comprise one or morephotoinitiators.

In embodiments described herein, the second precursor composition 369further comprises surface functionalized abrasive particles, such assurface functionalized ceria particles, surface functionalized aluminaparticles, surface functionalized silica particles, surfacefunctionalized silica/alumina oxide particles, or combinations thereof,and one or more dispersion and/or suspension agents. In addition toenabling the chemical bonding of abrasive particles to the polishing padmaterial of the polishing elements described herein, surfacefunctionalization of abrasive particles increases the compatibilitiesthereof with typical organic liquid resin precursor compositions. Thisincreased compatibility is the result of converting at least a portionof the hydrophilic hydroxyl surface terminated sites of the abrasiveparticles to hydrophobic polymerizable organic groups. This increasedcompatibility enables the surface functionalized abrasive particlesdescribed herein to enter into a suspension comprising a liquidprecursor composition and remain suspended therein, forming a highlystable and homogeneous suspension.

In addition, functionalizing the surfaces of the abrasive particlesdesirably increases the thermal stability and/or chemical compatibilityof precursor composition suspensions. While not wishing to be bound toany particular theory, it is believed that unmodified abrasive particlesact as a catalyst for polymerization (by initiating a thermal curingreaction at typical dispensing temperatures) of at least a portion ofthe components within a precursor composition. This prematurepolymerization undesirably increases the viscosity of the precursorcomposition which creates difficulties, such as nozzle clogging, whendispensing droplets thereof. Precursor compositions comprising surfacefunctionalized abrasive particles, with as few as less than about 5% ofthe abrasive particle's bonding sites bonded to polymerizable groups,such as between about 2% and about 5%, have increased thermal stabilityand/or chemical compatibility (i.e. improved viscosity for dispensingthrough the printer nozzles) when compared to precursor compositionscomprising untreated abrasive particles.

Herein, the concentration of the surface functionalized abrasiveparticles in at least the second precursor composition 369 is desirablymaintained at between about 1% and about 50% by weight, such as betweenabout 1 wt. % and about 40 wt. %, between about 1 wt. % and about 30 wt.%, between about 1 wt. % and about 20 wt. %, between about 1 wt. % andabout 10 wt. %, or between about 1 wt. % and about 5 wt. %, for exampleless than about 10 wt. % or less than about 5 wt. %. In otherembodiments, the surface functionalized abrasives comprise less thanabout 70 wt. % of the first precursor composition 359. In otherembodiments, surface functionalized abrasive particles and unmodifiedabrasive particles comprise less than about 70 wt. % of the firstprecursor composition 359.

Herein, functional polymers include multifunctional acrylates includingdi, tri, tetra, and higher functionality acrylates, such as1,3,5-triacryloylhexahydro-1,3,5-triazine or trimethylolpropanetriacrylate.

Functional oligomers include monofunctional and multifunctionaloligomers, acrylate oligomers, such as aliphatic urethane acrylateoligomers, aliphatic hexafunctional urethane acrylate oligomers,diacrylate, aliphatic hexafunctional acrylate oligomers, multifunctionalurethane acrylate oligomers, aliphatic urethane diacrylate oligomers,aliphatic urethane acrylate oligomers, aliphatic polyester urethanediacrylate blends with aliphatic diacrylate oligomers, or combinationsthereof, for example bisphenol-A ethoxylate diacrylate or polybutadienediacrylate. In one embodiment, the functional oligomer comprisestetrafunctional acrylated polyester oligomer available from Allnex Corp.of Alpharetta, Ga. as EB40® and the functional oligomer comprises analiphatic polyester based urethane diacrylate oligomer available fromSartomer USA of Exton, Pa. as CN991.

Monomers include both mono-functional monomers and multifunctionalmonomers. Mono-functional monomers include tetrahydrofurfuryl acrylate(e.g. SR285 from Sartomer®), tetrahydrofurfuryl methacrylate, vinylcaprolactam, isobornyl acrylate, isobornyl methacrylate, 2-phenoxyethylacrylate, 2-phenoxyethyl methacrylate, 2-(2-ethoxyethoxy)ethyl acrylate,isooctyl acrylate, isodecyl acrylate, isodecyl methacrylate, laurylacrylate, lauryl methacrylate, stearyl acrylate, stearyl methacrylate,cyclic trimethylolpropane formal acrylate, 2-[[(Butylamino)carbonyl]oxy]ethyl acrylate (e.g. Genomer 1122 from RAHN USACorporation), 3,3,5-trimethylcyclohexane acrylate, or mono-functionalmethoxylated PEG (350) acrylate. Multifunctional monomers includediacrylates or dimethacrylates of diols and polyether diols, such aspropoxylated neopentyl glycol diacrylate, 1,6-hexanediol diacrylate,1,6-hexanediol dimethacrylate, 1,3-butylene glycol diacrylate,1,3-butylene glycol dimethacrylate 1,4-butanediol diacrylate,1,4-butanediol dimethacrylate, alkoxylated aliphatic diacrylate (e.g.,SR9209A from Sartomer®), diethylene glycol diacrylate, diethylene glycoldimethacrylate, dipropylene glycol diacrylate, tripropylene glycoldiacrylate, triethylene glycol dimethacrylate, alkoxylated hexanedioldiacrylates, or combinations thereof, for example SR562, SR563, SR564from Sartomer®.

Reactive diluents include monoacrylate, 2-ethylhexyl acrylate,octyldecyl acrylate, cyclic trimethylolpropane formal acrylate,caprolactone acrylate, isobornyl acrylate (IBOA), or alkoxylated laurylmethacrylate.

Photoinitiators used herein include polymeric photoinitiators and/oroligomer photoinitiators, such as benzoin ethers, benzyl ketals, acetylphenones, alkyl phenones, phosphine oxides, benzophenone compounds andthioxanthone compounds that include an amine synergist, or combinationsthereof. For example, in some embodiments photoinitiators includeIrgacure® products manufactured by BASF of Ludwigshafen, Germany, suchas Irgacure 819, Irgacure 784, Irgacure 379, Irgacure 2022, Irgacure1173, Irgacure 500, combinations thereof, or equivalent compositions.

Dispersion and/or suspension agents are typically used to stabilize theabrasive particles within a liquid suspension, for example by increasingthe electrostatic repulsion (zeta potential) between abrasive particles.Dispersion and/or suspension agents can be used to enable the homogenoussuspension of surface functionalized abrasive particles in the liquid ofthe precursor compositions 359 and 369. Examples of dispersion and/orsuspension agents include Hyper® products, such as HypermerKD4 and HyperKD57, available from Croda, Inc., of New Castle, Del., USA, or BYKDis2008, BYK JET-9151, or BYK JET-9152 available from BYK-Gardner GmbHof Germany.

Typically, layers formed of the droplets of the precursor compositions359 and 369 dispensed by the printers 360 and 370 are cured by exposureto radiation 321 from a radiation source 320, such as an ultravioletlight (UV) source, x-ray source, or other type of electromagnetic wavesource. Herein, the radiation 321 is UV radiation provided by a UVsource. In other embodiments, the precursor compositions 359 and/or 369are cured by exposure to thermal energy.

FIG. 3B illustrates a curing process using the additive manufacturingsystem 350 of FIG. 3A. FIG. 3B shows a portion of one or more previouslyformed layers 346 of a polishing element, such as polishing element 204b-c, disposed on the manufacturing support 302. During processing, theprinters 360 and 370 deliver a plurality of droplets 343 of one or moreprecursor compositions, such as the second precursor composition 369, toa surface 346A of the one or more first layers 346. The plurality ofdroplets 343 form one of a plurality of second layers 348 which, in FIG.3B, includes a cured portion 348A and an uncured portion 348B where thecured portion has been exposed to radiation 321 from the radiationsource 320. Herein, the thickness of the cured portion 348A of the firstlayer is between about 0.1 micron and about 1 mm, such as between about5 microns and about 100 microns, for example between about 25 micronsand about 30 microns.

FIG. 3C is a close up cross-sectional view of a droplet 343 dispensedonto the surface 346A of the one or more previously formed layers 346.As shown in FIG. 3C, once dispensed onto the surface 346A, the droplet343 spreads to a droplet diameter 343A having a contact angle α. Thedroplet diameter 343A and contact angle α are a function of at least thematerial properties of the precursor composition, the energy at thesurface 346A (surface energy) of the one or more previously formedlayers 346, and time although the droplet diameter 343A and the contactangle α will reach an equilibrium after a short amount of time, forexample less than about one second, from the moment that the dropletcontacts the surface 346A of the one or more previously formed layers346. In some embodiments, the droplets 343 are cured before reaching anequilibrium diameter and contact angle. Typically, the droplets 343 havea diameter of between about 10 and about 200 micron, such as betweenabout 50 micron and about 70 microns before contact with the surface346A and spread to between about 10 and about 500 micron, between about50 and about 200 microns, after contact therewith.

Herein, the precursor compositions 359 and 369 are formulated to have aviscosity between about 80 cP and about 110 cP at about 25° C., betweenabout 15 cP and about 30 cP at about 70° C., or between 10 cP and about40 cP for temperatures between about 50° C. and about 150° C. so thatthe mixtures may be effectively dispensed through the dispense nozzles335 of the printers 360 and 370. In some embodiments, the secondprecursor composition 369 is recirculated or otherwise mechanicallyagitated to ensure that the surface functionalized abrasive particlesremain homogenously suspended in the liquid precursor mixture.

FIGS. 4A-4B illustrate the properties of a layer formed from a precursormixture comprising surface functionalized abrasive particles formedaccording to embodiments described herein. FIG. 4A is a TEM of a layerof polishing material having surface functionalized abrasives disposedtherein formed using the embodiments described in FIGS. 3A-3C from aprecursor having a formulation described in Table 2. In this embodiment,the surface functionalized ceria particles and a suspension agent weremixed in an acrylic monomer (IBOA) to form a mixture. The mixture wasmilled using a probe sonicator to break up larger agglomerations of theceria particles into smaller agglomerations or individual particleshaving a mean diameter between about 30 nm and about 300 nm. In otherembodiments, other types of milling processes, for example ball milling,are used to reduce larger agglomerations of abrasive particles todesirable sizes either before, during, or after mixing of the precursor.After milling, the remaining components of Table 2 were added to themixture to form the precursor composition which was homogenized byultrasonication so that the surface functionalized abrasive particleswere uniformly distributed therein. As shown in the images in FIG. 4Athe ceria particles have a uniform distribution within the printedlayer. FIG. 4B shows an EDX spectra of the ceria particles (shown ininset image 420) disposed in the layer formed from the precursor shownin Table 2 where Ce, O, and Si signals are attributable to ceriaparticles and the bonded dimethyl vinyl silane group which indicatessuccessful surface functionalization of the treated ceria particlesurfaces with the polymerizable dimethyl vinyl silane group.

TABLE 2 Component wt. % ceria 4.7% isobornyl acrylate (IBOA) 33.2% suspension agent (BYK9152) 1.5% chloro(dimethyl)vinylsilane 1.8%tetrafunctional acrylated polyester oligomer (EB40) 38.9%  aliphaticpolyester based urethane diacrylate  18% oligomer (CN991) Photoinitiator(Irgacure 819) 1.9%

FIG. 5 is a flow diagram illustrating a method 500 of forming apolishing pad, such as IA polishing pads 200 b-c of FIG. 2A-2B,according to embodiments described herein. At activity 510 the methodincludes dispensing a first plurality of droplets of a first precursor,such as the first precursor 359 described in FIGS. 3A-3C. Herein, thefirst precursor comprises a curable resin composition and is a mixtureof one or more functional polymers, functional oligomers, monomers,reactive diluents, or combinations thereof. In this embodiment, thefirst precursor further comprises one or more photoinitiators to enablecuring of the dispensed first plurality of droplets using UV radiation.Herein, the precursors used in method 500 have a viscosity between about80 cP and about 110 cP at about 25° C., between about 15 cP and about 30cP at about 70° C., or between 10 cP and about 40 cP for temperaturesbetween about 50° C. and about 150° C. enabling droplets therefrom to bedispensed through dispense nozzles 335 of the printer 360.

At activity 520 the method 500 includes curing the first plurality ofdroplets to form one of a plurality of first layers, such as the one ormore previously formed layers 346 shown in FIGS. 3B-3C, the one of theplurality of first layers herein comprising a portion of a sub-polishingelement, such as the sub-polishing elements 206 b-c of IA polishing pads200 b-c. Herein, the plurality of first droplets are cured by exposureto UV radiation from a UV radiation source, such as radiation source320, having a wavelength of between about 170 nm and about 500 nm.

At activity 530 the method 500 includes dispensing a second plurality ofdroplets of the first precursor and a second precursor onto theplurality of first layers, the second precursor comprising surfacefunctionalized abrasive particles having at least one polymerizablegroup chemically bonded to the surfaces thereof. Herein, the surfacefunctionalized abrasive particles comprise the reaction product ofhydroxyl terminated metal oxide nanoparticles, such as ceria, with anorganic compound, such as a silane organic compound, a cyanate compound,a sulfonic acid compound, a phosphoric acid organic compound, acarboxylic acid compound, or combinations thereof. In some embodiments,the reaction product of the hydroxyl terminated metal oxidenanoparticles and the organic compound forms an alkene terminatedabrasive particle. In this embodiment, the loading (% of surface siteschemically bonded to a polymerizable compound) is less than about 50%,for example less than about 50% of the surface sites are alkeneterminated, and the concentration of surface functionalized abrasiveparticles in the second precursor is between about 1 wt. % and about 50wt. %. In another embodiment, the total concentration of abrasiveparticles, including non-functionalized abrasive particles in the secondprecursor is less than about 70%.

Typically, the second precursor comprises a mixture of one or more oneor more functional polymers, functional oligomers, monomers, reactivediluents, or combinations thereof. In this embodiment, the secondprecursor further comprises a photoinitiator to enable UV curing and adispersion and/or suspension agent to stabilize the functionalizedabrasive particles in the second precursor mixture, and to maintaintheir suspension therein. In this embodiment, the surface functionalizedabrasive particles, or agglomerations thereof, have a mean diameter ofbetween about 10 nm and about 5 micron, such as between about 30 nm and500 nm, such as between about 30 nm and 300 nm, for example betweenabout 100 nm and about 150 nm.

At activity 540 the method 500 includes curing the second plurality ofdroplets to form a second layer, the second layer comprising portions ofthe sub-polishing element and portions of a plurality of polishingelements, such as the second polishing elements 204 b-c. Herein, curingthe second plurality of droplets comprises exposing the second pluralityof droplets to UV radiation thereby polymerizing the second plurality ofdroplets and forming chemical bonds at the interfaces therebetween. Inthis manner, chemical bonds, such as covalent and/or ionic bonds, areformed between polymer materials comprising portions of thesub-polishing element and polymer materials comprising portions of thepolishing elements at the interfaces thereof. Further, the surfacefunctionalized abrasive particles serve as a crosslinking reagentbetween reaction products of the second precursor mixture by formingchemical bonds therewith.

The method described above is used with the IA polishing pads describedherein or with any polishing pad where chemically bonding abrasiveparticles to the polishing pad material is desired. Benefits of themethod include forming IA polishing pads with tunable polishingproperties that are compatible with diamond conditioning during, before,or after a CMP process. Other embodiments comprise forming IA polishingpads by delivering droplets containing different precursors that havediffering concentrations of abrasive particles so that the abrasiveparticle concentration can be varied across the surface of the polishingpad material as shown in FIG. 6.

FIG. 6 is a schematic top view of an IA polishing pad 600 used with webbased or roll-to-roll type polishing system. The IA polishing pad 600 isformed using an additive manufacturing system, such as the additivemanufacturing system 350 shown in FIGS. 3A-3B. Herein, the IA polishingpad 600 is disposed over a polishing platen 652 between a first roll 681and a second roll 682. The IA polishing pad 600 comprises aconcentration gradient of abrasive particles bonded to the polishing padmaterial thereof across a polishing surface 608. Herein, the IApolishing pad 600 has a first region 602 comprising a low concentrationof abrasive particles, a second region 604 comprising a highconcentration of abrasive particles, and intermediate regions 603comprising intermediate concentrations of abrasive particles. Theregions 602 to 604 of varying concentrations of abrasive particles areformed according to embodiments herein from a plurality of precursorcompositions, each comprising a different concentration of surfacefunctionalized abrasive particles. In other embodiments, the regions ofvarying concentrations are formed by alternating droplets of a precursorcomposition comprising a high concentration of abrasive particles with aprecursor composition comprising a low concentration of abrasiveparticles.

While the foregoing is directed to embodiments of the presentdisclosure, other and further embodiments of the disclosure may bedevised without departing from the basic scope thereof, and the scopethereof is determined by the claims that follow.

The invention claimed is:
 1. A polishing article, comprising: asub-polishing element comprising a first reaction product of a firstprecursor; and a plurality of polishing elements extending from thesub-polishing element, the plurality of polishing elements comprising asecond reaction product of a second precursor, the second precursorcomprising functionalized abrasive particles, the functionalizedabrasive particles comprising alkene terminated groups, wherein thefunctionalized abrasive particles comprise a reaction product of metaloxide nanoparticles and a silane compound, a cyanate compound, asulfonic acid compound, a phosphoric acid compound, a carboxylic acidcompound, or combinations thereof, wherein less than about 50% ofbonding sites on surfaces of the functionalized abrasive particles arechemically bonded to a polymerizable compound.
 2. The polishing articleof claim 1, wherein portions of the plurality of polishing elements aredisposed in the sub-polishing element, and wherein a base polymermaterial of the sub-polishing element and a polymer pad material of theplurality of polishing elements are chemically bonded at interfacesthereof.
 3. The polishing article of claim 1, wherein the functionalizedabrasive particles, or agglomerations thereof, have a mean diameter ofbetween about 10 nm and about 5 micron.
 4. The polishing article ofclaim 1, wherein a concentration of functionalized abrasive particles inthe second precursor is between about 1 weight % and about 50 weight %.5. The polishing article of claim 1, wherein the second reaction productcomprises a polymer pad material and functionalized abrasive particlesdisposed in and chemically bonded to the polymer pad material.
 6. Thepolishing article of claim 1, wherein the second precursor comprisesfunctionalized abrasive particles having a polymerizable groupchemically bonded to surfaces thereof.
 7. The polishing article of claim1, wherein the second precursor comprises functionalized abrasiveparticles, or agglomerations thereof, having a mean diameter of betweenabout 10 nm and about 300 nm.
 8. The polishing article of claim 1,wherein the second precursor further comprises a mixture of one or morefunctional polymers, functional oligomers, monomers, reactive diluents,or combinations thereof.
 9. The polishing article of claim 8, whereinthe plurality of polishing elements have a medium or high modulus ofelasticity and the sub-polishing element has a low or medium modulus ofelasticity, and wherein the modulus of elasticity of the plurality ofpolishing elements is different from the modulus of elasticity of thesub-polishing element.
 10. The polishing article of claim 1, wherein theplurality of polishing elements and the sub-polishing element eachcomprise a material selected from the group consisting of polyamides,polycarbonates, polyesters, polyether ketones, polyethers,polyoxymethylenes, polyethersulfone, polyetherimides, polyimides,polyolefins, polysiloxanes, polysulfones, polyphenylenes, polyphenylenesulfides, polyurethanes, polystyrene, polyacrylonitriles, polyacrylates,polymethlymethacrylates, polyurethane acrylates, polyester acrylates,polyether acrylates, epoxy acrylates, polycarbonates, polyesters,melamines, polysulfones, polyvinyl materials, acrylonitrile butadienestyrene (ABS), halogenated polymers, block copolymers and randomcopolymers thereof.
 11. The polishing article of claim 1, wherein thesub-polishing element is formed by dispensing and curing a plurality ofdroplets of the first precursor, the plurality of polishing elements areformed by dispensing and curing a plurality of droplets of the secondprecursor, of the abrasive particles, and forming the plurality ofpolishing elements chemically bonds the functionalized abrasiveparticles to a polymer material of the plurality of polishing elements.12. A polishing article, comprising: a sub-polishing element comprisinga first reaction product of a first precursor; and a plurality ofpolishing elements extending from the sub-polishing element, theplurality of polishing elements comprising a second reaction product ofa second precursor, the second reaction product comprising a polymer padmaterial and abrasive particles disposed in and chemically bonded to thepolymer pad material, wherein the second precursor comprisesfunctionalized abrasive particles comprising alkene terminated groups,wherein the functionalized abrasive particles comprise a reactionproduct of metal oxide nanoparticles and a silane compound, a cyanatecompound, a sulfonic acid compound, a phosphoric acid compound, acarboxylic acid compound, or combinations thereof, wherein less thanabout 50% of bonding sites on surfaces of the functionalized abrasiveparticles are chemically bonded to a polymerizable compound.
 13. Thepolishing article of claim 12, wherein portions of the plurality ofpolishing elements are disposed in the sub-polishing element, andwherein a base polymer material of the sub-polishing element and thepolymer pad material of the plurality of polishing elements arechemically bonded at interfaces thereof.
 14. The polishing article ofclaim 12, wherein the functionalized abrasive particles, oragglomerations thereof, have a mean diameter of between about 10 nm andabout 5 micron.